Keyed circular cache

Fixed-size cache of items looked up by integer key, evicting the oldest item. More...

Data Structures
struct	KeyedCircularCache
	Keyed circular cache state. More...

Typedefs
typedef uint32_t	KeyedCircularCacheKey
	Key of a keyed circular cache.

Functions
void	keyed_circular_cache_init (KeyedCircularCache *c, KeyedCircularCacheKey *key_buffer, void *data_buffer, size_t item_size, size_t total_items)
	Initialize a keyed circular cache.
void *	keyed_circular_cache_get (KeyedCircularCache *c, KeyedCircularCacheKey key)
	Find an item by key.
void	keyed_circular_cache_push (KeyedCircularCache *c, KeyedCircularCacheKey key, const void *item)
	Copy an item into the cache, evicting the oldest one.

Detailed Description

Fixed-size cache of items looked up by integer key, evicting the oldest item.

Keys are stored apart from the items so lookups scan a compact array. Most recently pushed items are found first.

static KeyedCircularCacheKey s_keys[8];
static struct glyph s_glyphs[8];
static KeyedCircularCache s_cache;
 
keyed_circular_cache_init(&s_cache, s_keys, s_glyphs, sizeof(struct glyph), 8);
struct glyph *g = keyed_circular_cache_get(&s_cache, codepoint);
if (!g) {
  load_glyph(codepoint, &tmp);
  keyed_circular_cache_push(&s_cache, codepoint, &tmp);
}

---

Data Structure Documentation

KeyedCircularCache

struct KeyedCircularCache

Keyed circular cache state.

Data Fields
uint8_t *	cache_data	Item array.
KeyedCircularCacheKey *	cache_keys	Key array.
size_t	item_size	Size of an item in bytes.
size_t	next_item_to_erase_idx	Index of the next item to evict.
size_t	total_items	Number of items.

Typedef Documentation

KeyedCircularCacheKey

typedef uint32_t KeyedCircularCacheKey

Key of a keyed circular cache.

Function Documentation

keyed_circular_cache_get()

void * keyed_circular_cache_get	(	KeyedCircularCache *	c,
		KeyedCircularCacheKey	key
	)

Find an item by key.

Parameters

c	Cache.
key	Key.

Returns

Item in the cache, or NULL.

keyed_circular_cache_init()

void keyed_circular_cache_init	(	KeyedCircularCache *	c,
		KeyedCircularCacheKey *	key_buffer,
		void *	data_buffer,
		size_t	item_size,
		size_t	total_items
	)

Initialize a keyed circular cache.

The key array is used as is, so initialize it with keys that are never looked up.

Parameters

[out]	c	Cache.
	key_buffer	Key array of total_items keys.
	data_buffer	Item array of total_items items.
	item_size	Size of an item in bytes.
	total_items	Number of items.

keyed_circular_cache_push()

void keyed_circular_cache_push	(	KeyedCircularCache *	c,
		KeyedCircularCacheKey	key,
		const void *	item
	)

Copy an item into the cache, evicting the oldest one.

Parameters

c	Cache.
key	Key of the item.
item	Item, of the cache's item size.